Brightness enhancing films (BEF) have been used in lighting panels for directing light from lighting fixtures through luminaires, laptop computers displays, and flat panel desk top monitors or displays. The brightness enhancing films, which can have linear prisms, diffuse light with a desired directionality. Often the films have been used in combination with a fluorescent light source. The films have had partial success in improving luminaire or display brightness by controlling the angle at which light emerges.
Optical films are often used in combination with other films or sheets. For example, two diffuse films and two collimating films are used as a stack on a light guide behind liquid crystal displays. Optical layers with smooth surfaces in close contact can form subtle objectionable patterns of Newton's rings or “cloudy patches” of unintended light distortions where films contact another causing a “wet out” appearance.
Therefore, a need exists for reducing the wet out between films while maintaining brightness.